Controlled angular acceleration for air moving devices

ABSTRACT

Various methods related to air moving devices in electronic systems are disclosed. Various electronic systems including controlled air moving devices are also disclosed. Thus, in one method of controlling an air moving device in an electronic system, the air moving device is operable to accelerate between rotational speeds at a maximum angular acceleration. The method includes limiting an angular acceleration of the air moving device to a first acceleration limit less than the maximum angular acceleration when changing the air moving device from a first rotational speed to a second rotational speed.

FIELD

The present disclosure relates to air moving device control techniquesand electronic systems including controlled air moving devices.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Air moving devices (AMDs), e.g., fans, are commonly used for coolingelectronic systems. AMDs are commonly controlled using analog and/orsimple digital control techniques. Some of the common modes of operationfor AMDs include controlling AMD rotational speed based on ambienttemperature, controlling AMD rotational speed based on a differencebetween an inlet temperature and an outlet temperature of the electronicsystem including the AMD, controlling AMD rotational speed based on atemperature of a single component, device, etc. of an electronic systemincluding the AMD, controlling AMD rotational speed based on atemperature of more than one component, device, etc. of an electronicsystem including the AMD. The aforementioned modes of operation mayinclude over temperature protection and/or also consider a load on theelectronic system.

The inventors of the techniques, and systems disclosed herein haverealized that there are areas in which current AMD control techniquesand systems are lacking.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

According to an aspect of the present disclosure, a method ofcontrolling an air moving device in an electronic system is disclosed.The air moving device is operable to accelerate between rotationalspeeds at a maximum angular acceleration. The method includes limitingan angular acceleration of the air moving device to a first accelerationlimit less than the maximum angular acceleration when changing the airmoving device from a first rotational speed to a second rotationalspeed.

According to another aspect of this disclosure, a method of controllingan air moving device in an electronic system is disclosed. The airmoving device is operable to accelerate between rotational speeds at amaximum angular acceleration. The method includes selectivelycontrolling an angular acceleration of the air moving device whenchanging a rotational speed of the air moving device.

According to yet another aspect of this disclosure, an electronic systemincludes an air moving device selectively operable to rotate at aplurality of speeds in response to a control signal and a controllercommunicatively coupled to the air moving device. The controller isconfigured to generate the control signal and to selectively control anangular acceleration of the air moving device through the control signalwhen changing a rotational speed of the air moving device.

In another aspect of this disclosure, a method of controlling an airmoving device in an electronic system in response to a change in anoperating parameter of the electronic system is disclosed. The methodincludes delaying a change in a rotational speed of the air movingdevice in response to the change in the operating parameter.

According to an aspect of this disclosure, an electronic system includesan air moving device, a sensor for monitoring an operating parameter ofthe electronic system and generating a signal representative of theoperating parameter, and a controller for controlling the air movingdevice. The controller is configured to selectively control a rotationalspeed of the air moving device, to receive the signal representative ofthe operating parameter, and to delay changing the rotational speed ofthe air moving device in response to the signal representative of theoperating parameter.

In another aspect of this disclosure, an electronic system includes afirst air moving device, a second air moving device, and a controllerfor controlling the first air moving device and the second air movingdevice. The controller is configured to selectively determine a targetrotational speed for the first air moving device and the second airmoving device. The controller is configured to control the first andsecond air moving devices to operate at a rotational speed approximatelyequal to the target rotational speed and a first rotational speed of thefirst air moving device is greater than a second rotational speed of thesecond moving device.

In yet another aspect of this disclosure, a method of controlling aplurality of air moving devices in an electronic system is disclosed.The method includes determining a target rotational speed for aplurality of fans and transmitting different control signals to theplurality of air moving devices. The different control signals cause theplurality of air moving devices to rotate at a plurality of differentspeeds near the target rotational speed and no two air moving devices ofthe plurality of air moving devices rotate at a same rotational speed.

According to still another aspect of this disclosure, an electronicsystem includes an air moving device and a controller for controllingthe air moving device. The controller is configured to selectivelycontrol a rotational speed of the air moving device. The controller isconfigured to vary the rotational speed within a range bounded by andincluding a first rotational speed and a second rotational speed duringa time that a target rotational speed is within the range.

In a further aspect of this disclosure, a method of controlling an airmoving device in an electronic system includes varying a rotationalspeed of the air moving device within a range of rotational speeds thatincludes an intended rotational speed.

According to another aspect of this disclosure, an electronic systemincludes a memory storing data about a plurality of different models ofair moving devices useable in the electronic system, and a controllerfor controlling the air moving device. The data includes at least oneoperating characteristic for each of the plurality of different modelsof air moving device. The controller is configured to monitor a responsecharacteristic of the air moving device, compare the monitored responsecharacteristic with operating characteristics stored in the memory,determine a model of the air moving device, and set operation parametersfor the air moving device based on the stored data about said model ofair moving device.

According to a further aspect of this disclosure, a method includesmonitoring an operating condition of an electronic system, monitoring anoperation characteristic of an air moving device in the electronicsystem, storing data over time of the operation characteristic of theair moving device of the air moving device correlated to the operatingcondition of the electronic system when the operation characteristic wasmonitored, and estimating a remaining life of the air moving devicebased on the stored data.

According to still another aspect of this disclosure, an electronicsystem includes an air moving device, a sensor for monitoring atemperature in the electronic system and generating a temperaturesignal, a memory, and a controller for controlling the air movingdevice. The controller is configured to monitor a rotational speed ofthe air moving device, to monitor the temperature via the temperaturesignal, and to store data over time to the memory including a durationof the rotational speed correlated with the monitored temperature forthat duration.

According to yet another aspect of this disclosure, a method includesmonitoring an operation characteristic of an air moving device in theelectronic system, storing data over time of the operationcharacteristic of the air moving device, comparing the monitoredoperation characteristic with the stored data, and detecting, based onthe comparison with the stored data, an impending failure of the airmoving device.

In another aspect of this disclosure, an electronic system includes anair moving device, a memory, and a controller for controlling the airmoving device. The controller is configured to monitor a current of theair moving device, to store data over time to the memory including thecurrent of the air moving device, and to detect an impending failure ofthe air moving device based on the monitored current.

According to another aspect of this disclosure, an electronic systemincludes a plurality of air moving devices, a controller configured tocontrol the plurality of air moving devices, and a user interface toallow a user to select an operating profile from a plurality ofoperating profiles for the plurality of air moving devices. Theplurality of operating profiles includes a high efficiency profile, alow acoustic noise profile, a high cooling profile and a long lifeprofile.

Some example embodiments of methods and electronic systems incorporatingone of more of these aspects are described below. Additional aspects andareas of applicability will become apparent from the description below.It should be understood that various aspects of this disclosure may beimplemented individually or in combination with one or more otheraspects. It should also be understood that the description and specificexamples herein are provided for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a block diagram of an electronic system including a controllerhaving memory and a plurality of air moving devices according to aspectsof this disclosure.

FIG. 2 is a block diagram of another electronic system including acontroller, a memory and a plurality of air moving devices according toaspects of this disclosure.

FIG. 3 is a functional block diagram of a controller for controlling airmoving devices in an electronic system according to various aspects ofthis disclosure.

FIG. 4 is a histogram illustrating an example data correlating ranges ofrotational speed of air moving devices and ranges of temperatures in anelectronic system including the air moving devices.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises,” “comprising,” “including,” and“having,” are inclusive and therefore specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The method steps, processes, and operations described hereinare not to be construed as necessarily requiring their performance inthe particular order discussed or illustrated, unless specificallyidentified as an order of performance. It is also to be understood thatadditional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto,” “directly connected to,” or “directly coupled to” another elementor layer, there may be no intervening elements or layers present. Otherwords used to describe the relationship between elements should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” etc.). As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

Although the terms first, second, third, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms may be only used to distinguishone element, component, region, layer or section from another region,layer or section. Terms such as “first,” “second,” and other numericalterms when used herein do not imply a sequence or order unless clearlyindicated by the context. Thus, a first element, component, region,layer or section discussed below could be termed a second element,component, region, layer or section without departing from the teachingsof the example embodiments.

An electronic system, generally indicated by reference numeral 100,embodying aspects of the present disclosure is shown in FIG. 1. Theelectronic system 100 includes air moving devices (AMDs) 102A, 102B(sometimes collectively referred to as AMDs 102) and a controller 104for controlling the AMDs 102.

The controller 104 is a digital controller such as, for example, amicroprocessor, etc. The controller 104 is communicatively coupled tothe AMDs 102. The controller 104 generates a first control signal andprovides the control signal to the AMD 102A to cause the AMD 102A tooperate as desired by the controller 104. The controller 104 generates asecond control signal and provides the control signal to the AMD 102B tocause the AMD 102B to operate as desired by the controller 104. Thecontrol signal may be any appropriate control signal for controllingoperation of the AMDs 102 including, for example a pulse width modulated(PWM) control signal, a voltage, etc. When a PWM signal is used, theduty cycle of the PWM control signal instructs (or directly controls)the rotational speed of the AMD 102.

The AMDs 102 may be any suitable type of air moving device for use inthe electronic system 100. In various embodiments, the AMDs 102 arefans. Although two AMDs 102 are illustrated in FIG. 1, more or fewerAMDs 102 may be included in the electronic system 100. Further, each AMD102 may be an array of AMDs. An array of AMDs commonly includes morethan one AMD 102 to be commonly operated (e.g., at the same time and atthe same speed, etc.). The AMDs 102 may each include a tachometer forproviding a signal representative of its rotational speed to thecontroller 104. Alternatively, a separate sensor, or sensors, may beused to generate a signal representative of the rotational speed of oneor more AMD 102. Each AMD 102 is selectively controllable at variousspeeds between a minimum rotational speed (typically greater than zeroand determined by the design and construction of the AMD 102) and amaximum rotational speed. Each AMD 102 will commonly have a maximumangular acceleration that is the fastest that the AMD 102 may acceleratebetween rotational speeds. As used herein, angular acceleration includeschanging rotational speeds to speed up and/or slow down an AMD 102(e.g., to include what is commonly referred to as acceleration anddeceleration). A positive angular acceleration indicates a rotationalspeed increasing over time, while a negative angular accelerationindicates a rotational speed decreasing over time.

The controller 104 includes memory 106. The memory 106 typically willinclude instructions (e.g., software, firmware, etc.) for the controller104. The instructions may configure the controller 104 to operate theAMDs 102 in a particular manner, monitor various operating parameters ofthe AMDs 102, monitor various operating conditions of the electronicsystem 100, etc. The memory 106 may also be used by the controller 104to store data concerning the AMDs 102, and/or the electronic system 100,etc.

The controller 104 can monitor various operating conditions of theelectronic system 100. For example, the electronic system 100 includes atemperature sensor 108. Temperature sensor 108 senses a temperature andprovides a temperature signal representative of the sensed temperatureto the controller 104. The sensed temperature may be any temperature.For example, the temperature may be an ambient temperature in the roomin which the electronic system 100 is located, an ambient temperature inthe electronic system 100, a temperature on and/or near a component ofthe electronic system 100, a temperature at an air inlet of theelectronic system 100, a temperature at an air outlet of the electronicsystem 100, etc. Although only one temperature sensor 108 isillustrated, the electronic system 100 may include more than onetemperature sensor 108. When multiple temperature sensors 108 areincluded, each temperature sensor 108 may be used to monitor a differenttemperature. For example, one temperature sensor 108 may sense anambient temperature in the electronic system 100, one temperature sensor108 may sense a temperature on and/or near a component of the electronicsystem 100, another temperature sensor 108 may sense a temperature at anair inlet of the electronic system 100, yet another temperature sensor108 may sense a temperature at an air outlet of the electronic system100, etc. The temperature signal(s) received by the controller 104 maybe used for any suitable purpose including, for example, for determininga target (e.g. desired, goal, optimal, etc.) rotational speed for theAMDs 102, for detecting problems with one or more of the AMDs 102 and/orthe electronic system 100, etc.

The electronic system 100 also includes a current sensor 110. Thecurrent sensor 110 senses the electrical current provided to the AMDs102 and provides a signal representative of the current to thecontroller 104. Although one current sensor 110 is illustrated, in someembodiments, the electronic system 100 may include more than one currentsensor 110 or no current sensor 110. In some embodiments, the electronicsystem 100 may include a separate current sensor 110 for each AMD 102.The current signal(s) received by the controller 104 may be used for anysuitable purpose including, for example, for controlling the rotationalspeed of the AMDs 102, for detecting problems with one or more of theAMDs 102 and/or the electronic system 100, etc. The current sensor 110may be any suitable type of current sensor including, for example, acurrent sense resistor, current transformer, a Hall Effect sensor, etc.

The electronic system 100 includes an airflow sensor 112. The airflowsensor 112 senses an airflow in the electronic system 100 and provides asignal representative of the airflow to the controller 104. The sensedairflow may be any airflow in the electronic system 100. For example,the airflow may be an airflow through an inlet to the electronic system100, an airflow through an outlet of the electronic system 100, aninflow on and/or near a component of the electronic system 100, etc.Although one airflow sensor 112 is illustrated, the electronic system100 may include more than one airflow sensor 112 or no airflow sensor112. The airflow signal(s) received by the controller 104 may be usedfor any suitable purpose including, for example, for determining atarget rotational speed of the AMDs 102, for detecting problems with oneor more of the AMDs 102 and/or the electronic system 100, etc.

The electronic system 100 includes a pressure sensor 114. The pressuresensor 114 senses a pressure in the electronic system 100 and provides asignal representative of the pressure to the controller 104. The sensedpressure may be any pressure in the electronic system 100. For example,the pressure may be a pressure at an inlet to the electronic system 100,a pressure at an outlet of the electronic system 100, etc. Although onepressure sensor 114 is illustrated, the electronic system 100 mayinclude more than one pressure sensor 114 or no pressure sensor 114. Thepressure signal(s) received by the controller 104 may be used for anysuitable purpose including, for example, for determining a targetrotational speed of the AMDs 102, for detecting problems with one ormore of the AMDs 102 and/or the electronic system 100, etc.

In FIG. 2, another embodiment of an electronic system 200 includes acontroller 204 and memory 206. The memory 206 is not part of thecontroller 204. In all other respects, the electronic system 200 issimilar to the electronic system 100.

The aspects described herein may be utilized individually or combined invarious combinations in an electronic system. An example embodiment of acontroller 304 embodying the aspects described herein for controllingoperation of an AMD is illustrated in FIG. 3. The controller 304 may beused in any of the electronic systems described herein (e.g., system100, 200). The various blocks of the system 300 may be functionalinstruction blocks of the controller 304, may be physical components ofthe controller, or may be combinations of physical components andfunctional instructional blocks.

Also shown in FIG. 3 is a graphical user interface (GUI) for interfacingwith the controller 304. The GUI may be part of the controller 304, maybe part of the electronic system including the controller 304 (e.g.,system 100, 200), may be part of a system hosting the electronic systemincluding the controller 304, or may be part of a separate system.

Various aspects of this disclosure will be discussed with reference tothe electronic system 100. It should be understood that the variousaspects are applicable to other electronic systems including, forexample, the electronic system 200 of FIG. 2. It should also beunderstood that the controller 104 discussed below may be or include thecontroller 304.

The rotation of the AMDs 102 commonly generates acoustic noise that aperson located near the electronic system 100 may hear and perceive.Sudden and/or rapid changes in the rotational speed of the AMDs 102 maybe particularly noticeable.

According to an aspect of the present disclosure, a method ofcontrolling an air moving device in an electronic system is disclosed.The air moving device is operable to accelerate between rotationalspeeds at a maximum angular acceleration. The method includes limitingan angular acceleration of the air moving device to a first accelerationlimit less than the maximum angular acceleration when changing the airmoving device from a first rotational speed to a second rotationalspeed.

According to another aspect of this disclosure, a method of controllingan air moving device in an electronic system is disclosed. The airmoving device is operable to accelerate between rotational speeds at amaximum angular acceleration. The method includes selectivelycontrolling an angular acceleration of the air moving device whenchanging a rotational speed of the air moving device.

The controller 104 may determine to change the rotational speed of anAMD 102 for various reasons. The controller 104 may be commanded tochange the rotational speed of one or more AMD 102. For example, thecontroller 104 may receive a signal indicating the electronic system 100is starting-up or shutting down, a user may directly instruct thecontroller 104 (such as via a user interface) to change the rotationalspeed of a particular AMD 102, all AMDs 102, some combination of AMDs102, etc. The controller 104 may additionally, or alternatively,determine that the rotational speed of one or more AMD 102 should bechanged in response, for example, to a temperature signal, an air-flowsignal, etc.

When the controller 104 is to change the rotational speed of an AMD 102from a first rotational speed to a second rotational speed, thecontroller 104 changes the rotational speed of the AMD 102 whilecontrolling the angular acceleration of the AMD 102. The controller 104may limit the angular acceleration to a level that is less than themaximum angular acceleration. In some instances, as will be discussedbelow for example, the controller 104 may permit the AMD 102 toaccelerate with its maximum angular acceleration. In contrast, if thecontroller 104 were to simply command the AMD 102 to change speed by,for example, simply changing the control signal to the AMD 102 to acontrol signal for the desired speed, the AMD 102 receiving the signalwould typically accelerate at its maximum angular acceleration to thenewly commanded speed. This uncontrolled acceleration may increaseperceptible acoustic noise.

The controller 104 may control the angular acceleration of the AMDs 102by various methods. For example, the controller 104 may adjust thecontrol signal to the appropriate AMD 102 in a series of steps until therotational speed of the AMD 102 reaches the desired rotational speed.The steps may be a series of PWM duty cycle steps, a series of voltagelevel steps, or other control signal steps, depending on the controlsignals appropriate to the particular AMD 102.

The angular acceleration may be controlled to maintain a constantangular acceleration, to vary angular acceleration proportional to therotational speed, to vary the angular acceleration depending on whetherthe angular acceleration is positive or negative, to vary the angularacceleration based on a logarithmic division of the rotational speedchange, to vary the angular acceleration using square, trapezoidal,sinusoidal, etc. waveforms, or according to any other suitable manner.

In some embodiments employing a constant rate angular acceleration, thecontroller 104 limits the positive angular acceleration to two hundredand fifty rpm per second (250 rpm/s) or less and limits the negativeangular acceleration to four hundred and fifty rpm per second (450rpm/s) or less. In other embodiments, other positive and/or negativeacceleration rates may be employed. Angular acceleration of an AMD 102may be less audibly perceptible when the acceleration is negative thanwhen it is positive, permitting the angular acceleration to be largerwhen the angular acceleration is negative without increasing theperceptible noise over that generated when the angular acceleration ispositive.

Acoustic noise generated by acceleration of an AMD 102 may be moreperceptible to a listener when the AMD 102 is rotating at lower speedsand less perceptible when the AMD 102 is rotating at higher rotationalspeed. Thus, in some embodiments, the angular acceleration is variedbased on the rotational speed of the AMD 102. The range of possiblespeeds of the AMD 102 is divided into several ranges. The controller 104controls the angular acceleration based on which range the rotationalspeed of the AMD 102 is in at that time. The manner in which the angularacceleration is controlled, as well as the resulting acceleration, mayvary between the ranges. For example, angular acceleration may beincreased linearly in all of the ranges, but the magnitude of theangular acceleration may differ between ranges. Alternatively, oradditionally, the angular acceleration may be controlled linearly in oneor more ranges and controlled in a different manner in one or morerange. In some embodiments, the AMD 102 is permitted to accelerate atabout its maximum angular acceleration when the rotational speed iswithin at least one of the ranges. In some embodiments, the controller104 permits greater magnitude angular acceleration of the AMDs 102 whenthe rotational speed is in a higher rotational speed range than when therotational speed is in a lower rotational speed range.

According to another aspect of this disclosure, a method of controllingan air moving device in an electronic system in response to a change inan operating parameter of the electronic system is disclosed. The methodincludes delaying a change in a rotational speed of the air movingdevice in response to the change in the operating parameter.

As discussed above, the controller 104 may determine to change therotational speed of an AMD 102 for various reasons. The controller 104may be commanded to change the rotational speed of one or more AMD 102and/or the controller 104 may determine that the rotational speed of oneor more AMD 102 should be changed in response to an operating parametersuch as, for example, a temperature signal, an air-flow signal, etc.

The change in the rotational speed of the AMD 102 may be delayed for afixed length of time or a variable length of time. For example, thecontroller 104 may delay changing the rotational speed of the AMD 102for a length of time that varies based on a magnitude of the change tobe implemented. Thus, for example, if the temperature sensor 108indicates a large change in the temperature and the controller 104determines to greatly increase the rotational speed of the AMDs 102, thetime delay may be very short (or even no delay) in order to decrease thelikelihood of damage to the electronic system 100 caused by excessivetemperature. Conversely, if the temperature sensor 108 indicates a smallchange in the temperature and the controller 104 determines to onlyslightly increase the rotational speed of the AMDs 102, the time delaymay be relatively long. If the temperature indicated by the temperaturesignal decreases before the controller 104 increases the speed of theAMDs 102, the controller 104 may not need to change the speed of theAMDs 102 at all. Thus, the delay may prevent the controller 104 fromunnecessarily changing the speed of the AMDs 102 in response tomomentary fluctuations of the monitored operating parameter (whethercaused by actual fluctuations, erroneous sensor signals, etc.).

The amount of delay may also be related to the magnitude of themonitored operating parameter. For example, the controller 104 may delayfor a shorter time (including no delay) if the operating parameter is atemperature and the temperature is already relatively high. Because hightemperatures may damage the electronic system 100, or componentsthereof, relatively quickly, it may be desirable to include only a shortdelay, or no delay at all, when the temperature is relatively high inorder to limit the likelihood of damage to the electronic system 100.Conversely, when the temperature is low, and the risk of damage to theelectronic system is lower, the controller 104 may delay changing therotational speed of the AMDs 102 for a longer length of time.

The length of time of the delay may additionally, or alternatively, varyby being based on the change in the value of the monitored operatingparameter. In such embodiments, the controller 104 is configured not tochange the rotational speed of the AMDs 102 until the operatingparameter reaches a threshold. The threshold may be a fixed value or maybe a value relative to the initial operating parameter value. Forexample, the controller 104 may be configured not to change the speed ofthe AMD 102 until the temperature signal indicates that the temperaturehas increased or decreased by five degrees. Similarly, the controller104 may be configured not to change the speed of the AMD 102 until thetemperature indicated by the temperature signal has increased ordecreased by five percent. The threshold above and below the initialvalue need not be the same. Hence, for example, the controller may beconfigured not to change the speed of the AMD 102 until the temperatureincreases by five degrees or decreases by ten degrees.

The amount of delay, or whether any delay is used, may vary between AMDs102. For example, if AMD 102A is directly cooling a highly temperaturesensitive component of the electronic system 100, the controller may beconfigured not to delay any changes in the speed of AMD 102A. Despiteintroducing no delay into changes in the speed of AMD 102A, if AMD 102Bis not cooling a highly temperature sensitive component, the controller104 may delay changing the speed of AMD 102B according to the aspectsdisclosed herein.

In various embodiments, introduction of delay into the control of theAMDs 102 may provide benefits to the electronic system 100 including,for example, more energy efficient operation, more stable cooling, loweracoustic noise, etc.

According to another aspect, a controller for an air moving device in anelectronic system transforms output signals of the air moving device toa format expected by a system hosting the electronic system andtransforms signals from the system hosting the electronic system to aformat usable by the air moving device.

In various embodiments, the electronic system 100 is hosted by (e.g.,incorporated in, coupled to, part of, etc.) another system. The hostsystem may not know the type of AMD 102 and may not know the format ofsignal needed to control the AMD 102. Thus, the controller 104 acts asan interpreter to transform signals between the host system and the AMD102. The controller 104 is configured to receive signals from the hostsystem (e.g., commanded speed signals, etc.) and output appropriatecontrol signals to the AMDs 102. Feedback from the AMDs 102 (e.g.,tachometer signals), may also be converted by the controller 104 to theformat expected by the host system. Accordingly, the host system notonly may not know the type of AMD 102, but also need not know the typeof AMD 102. This may permit, among other things, any type of AMD 102 beused in the electronic system 100

In one example embodiment, the electronic system 100 is incorporated ina host system. The host system expects to control airflow from the AMDs102 using analog voltage control and to monitor the rotational speed ofthe AMDs 102. The AMDs 102, however, are controlled by PWM controlsignals and have rotational speed and airflow characteristics thatdiffer from those expected by the host system. Further, the host systemrequires that any demand above a certain voltage be treated asexceptional and requires the AMDs 102 operate at full speed. The PWMcontrol signal duty cycle and corresponding rotational speed of the AMDs102 at various airflow rates are calculated. The relationship betweenthe control voltages generated by the host system and the correspondingPWM signal is mapped and stored to the memory 106 in, for example, alook-up table. Similarly, the actual rotational speed for the AMDs 102and the speed expected by the host system for various control signalsare mapped and stored to the memory 106. Thus, when the host systemoutputs a voltage level, thereby indirectly commanding a particularairflow, the controller 104 looks up the corresponding PWM signal neededto operate the AMDs 102 to produce the commanded airflow and providesthe appropriate PWM control signal to the AMDs 102. Similarly, thecontroller can look up the speed signal received from the AMDs 102 toconvert it to the speed signal expected by the host system for the speedat which the AMDs 102 are actually operating. This function of thecontroller 104 is transparent to the host system. The host system isunaware that the AMDs 102 are not the type of AMDs that it is expectingand for which it is outputting control signals and monitoring speed.This may permit any AMD 102 that can be appropriately mapped to be usedin a host system without the host system needing to be reprogrammed,reconfigured, etc.

According to yet another aspect of the present disclosure, a method ofcontrolling a plurality of air moving devices in an electronic system isdisclosed. The method includes determining a target rotational speed fora plurality of fans and transmitting different control signals to theplurality of air moving devices. The different control signals cause theplurality of air moving devices to rotate at a plurality of differentspeeds near the target rotational speed and no two air moving devices ofthe plurality of air moving devices rotate at a same rotational speed.

When two air moving devices of the same type receive the same controlsignal, the two air moving devices theoretically will operate at thesame nominal speed. For various reasons including, for example,manufacturing differences between the different individual air movingdevices (even those of a same model from a same manufacturer), distancefrom the controller 104, effects from other components nearby,temperature differences, debris, wear of the particular air movingdevice, etc., the actual rotational speed of the air moving devices areoften slightly different. When two air moving devices operate at nearly,but not quite, the same speed, they generate two acoustic waves ofnearly the same frequency. These two waves may combine producing aresultant wave that is modulated by the difference in their frequencies.This produces a phenomenon known as beating. Beating may result inaudible oscillations of the noise level of the air moving devices.

Thus, in some embodiment, the controller 104 deliberately separates therotational speeds of two air moving devices (e.g., 102A and 102B) thatwould otherwise be driven at the same nominal rotational speed. Thecontrol signals to one or both of the AMDs 102 may be altered. One AMD102 may be driven at the nominal, target rotational speed, while theother AMD 102 is driven at a higher or lower speed. Alternatively, oneAMD 102 may be driven at a rotational speed above the target rotationalspeed, while the other AMD 102 is driven at a speed below the targetrotational speed. The amount of separation between the speed of thefirst AMD 102 and the second AMD 102 may be sufficient to limit oreliminate beating.

According to still another aspect of this disclosure, a method ofcontrolling an air moving device in an electronic system comprisesvarying a rotational speed of the air moving device within a range ofrotational speeds that includes an intended rotational speed.

In some embodiments according to this aspect, the controller 104 isconfigured to vary the control signals provided to the AMDs 102 within arange of rotational speeds that contains the intended rotational speedfor the AMDs 102. Thus, instead of simply providing a control signal tocause the AMDs 102 to operate at the intended rotational speed, thecontroller 104 provides different control signals over time to cause therotational speed of the AMDs 102 to vary over time within a band aroundthe intended rotational speed. The upper and lower limits of the range(sometimes called a band) may be defined by a first rotational speedabove and a second rotational speed below the intended rotational speed.

The rotational speed of the AMDs 102 may be varied by, for example,cycling the rotational speed between the first rotational speed, theintended rotational speed and the second rotational speed. Therotational speed of the AMDs 102 may be swept between the firstrotational speed and the second rotational speed. The rotational speedof the AMDs 102 may be randomly or pseudo-randomly varied amongrotational speed within the range. Any other suitable method of varyingthe rotational speed of the AMDs 102 may also be used.

Discrete acoustic tones may be generated by AMDs 102, particularly at apole pass frequency and higher harmonics thereof. These tones can bedistinct and may be known as prominent tones when they exceed an ambientacoustic noise level by a sufficient margin. By introducing variationinto the control signals provided to the AMDs 102, as discussed herein,prominent tones may be eliminated or reduced.

According to another aspect of this disclosure, a controller forcontrolling an air moving device in an electronic system is configuredto monitor a response characteristic of the air moving device, comparethe monitored response characteristic with operating characteristicsstored in memory of the electronic system, determine a model of the airmoving device, and set operation parameters for the air moving devicebased on the stored data about said model of air moving device.

Thus, by this aspect, the electronic system 100 may automaticallydetermine what type of air moving device the AMDs 102 are andappropriate control parameters for that type of air moving device may beset by the controller 104 for use in controlling the AMDs 102.

In some embodiments, the memory 106 includes data about a plurality ofdifferent models of air moving devices useable in the electronic system100. The data includes at least one operating characteristic for each ofthe plurality of different models. The operating characteristic may be,for example, rotational speed in response to a prescribed controlsignal, time to change speed between prescribed limits, a minimumrotational speed, maximum rotational speed, temperature, airspeed, airpressure, etc. in response to a prescribed control signal, etc. One ormore of such operating characteristics for each model of air movingdevice may be stored in the memory 106. Accordingly, the controller 104may operate (or attempt to operate) the AMDs 102 and may monitor one ormore of the operating characteristics. The monitored operatingcharacteristic(s) are compared by the controller 104 to the stored datain the memory 106 to determine what model of air moving device the AMDs102 are. Once the model is known, the controller 104 may set appropriateoperating parameters for controlling the AMDs 102 based on the dataabout that model stored in the memory 106.

According to another aspect of this disclosure, a method includesmonitoring an operating condition of an electronic system, monitoring anoperation characteristic of an air moving device in the electronicsystem, storing data over time of the operation characteristic of theair moving device correlated to the operating condition of theelectronic system when the operation characteristic was monitored, andestimating a remaining life of the air moving device based on the storeddata.

In some embodiments, the controller 104 monitors an operationcharacteristic of the air moving devices 102 and stores data about theoperation characteristic to the memory 106. The operation characteristicmay be any suitable operation characteristic of the AMDs 102 including,for example the rotational speed of the AMDs 102, number of on/offcycles of the AMDs 102, etc. Thus, in some embodiments, the controller104 stores data indicating the length of time the AMDs 102 were operatedat a particular speed.

The controller 104 also monitors and stores data concerning an operatingcondition of the electronic system 100. The operating condition may be,for example, the temperature detected by the temperature sensor 108, aload attached to the electronic system (if, for example, the electronicsystem is a power supply), etc. The operating condition data is alsostored to the memory 106 and is correlated with the operationcharacteristic data. Thus, for example, the data stored in the memory106 may indicate not only how long the AMDs operated at a particularspeed, but what the temperature in the electronic system was during thattime.

The data monitored may be stored as discrete values or may be mapped tocategories (also referred to as ranges). For example, the possiblerotational speeds may be assigned to two or more ranges and thetemperature may be assigned to two or more ranges. The data stored inmemory would indicate how long the AMDs 102 operated in a first speedrange while the temperature was within a first temperature range.Similarly, the data would indicate how long the AMDs 102 operated withina second speed range while the temperature was within the firsttemperature range and how long the AMDs 102 operated within the firstspeed range while the temperature was within a second temperature range,etc. Although two speed ranges and two temperature ranges werediscussed, more or fewer ranges of operating conditions and operationcharacteristics may be used. Further more than one operating conditionand/or more than one operation characteristic may be used. For examplethe controller 104 may monitor and store to the memory 106, therotational speed of the AMDs 102, the current provided to the AMDs, theambient temperature of the room in which the electronic system islocated, the ambient temperature within the electronic system, etc. FIG.4 is a histogram illustrating an example of such data correlating rangesof rotational speed of the AMDs 102 and ranges of temperatures.

The data thus stored in the memory 106 may be used to estimate theremaining life (or the estimated time to failure) of the AMDs 102. Insome embodiments, the controller 104 estimates the remaining life of theAMDs 102. In some embodiments, the data stored in the memory 106 may beoutput from the electronic system 100 to another system for estimatingthe remaining life of the AMDs 102. The other system may be an unrelatedsystem or may be a system hosting the electronic system 100.

According to another aspect of this disclosure, a method includesmonitoring an operation characteristic of an air moving device in theelectronic system, storing data over time of the operationcharacteristic of the air moving device, comparing the monitoredoperation characteristic with the stored data, and detecting, based onthe comparison with the stored data, an impending failure of the airmoving device.

In some embodiments, the controller 104 monitors an operationcharacteristic of the air moving devices 102 and stores data about theoperation characteristic to the memory 106. The operation characteristicmay be any suitable operation characteristic of the AMDs 102 including,for example the rotational speed of the AMDs 102, number of on/offcycles of the AMDs 102, electrical current provided to the AMDs 102,etc. The stored data may be correlated to other data such as, forexample, an operating condition of the electronic system 100 or may beuncorrelated.

The controller 104 may compare the monitored operation characteristic tothe data stored to the memory 106, effectively comparing currentoperation characteristics with historical operation characteristicsincluding, for example the original operation characteristics of theAMDs 102. By making such comparisons, the controller may detect certainimpending failures of the AMDs 102. For example a gradual increase incurrent over time may indicate an AMD 102 is likely to fail.Accordingly, in some embodiments, the controller 104 is configured toprovide an alert when the current, detected, for example, by the currentsensor 110, reaches a threshold value. In some embodiments, thecontroller 104 is configured to provide an alert when one or moreoperation characteristic exhibits sudden or erratic changes.

According to still another aspect of this disclosure, an electronicsystem includes a plurality of air moving devices, a controllerconfigured to control the plurality of air moving devices, and a userinterface to allow a user to select an operating profile from aplurality of operating profiles for the plurality of air moving devices.The plurality of operating profiles includes a high efficiency profile,a low acoustic noise profile, a high cooling profile and a long lifeprofile.

Thus, in some embodiments, the electronic system 100 includes a userinterface (e.g., graphic user interface, etc.) to allow a user to selectan operating profile from a plurality of profiles. The controller 104 isconfigured to operate the AMDs 102 according to the selected operatingprofile. In some embodiments, the selectable operating profiles mayincorporate one or more aspects described above.

The selectable operating profiles may include a high efficiencyoperating profile. Air moving devices may operate at maximum efficiencyaround the center of their range of rotational speeds. Electronicsystems, however, often operate more efficiently when temperatures arelower. The high efficiency operating profile attempts to balanceefficiency of the AMDs 102 with the efficiency of the electronic system100. In some embodiments, the controller 104 may be configured tooperate with high efficiency by measuring input power and output powerof the electronic device at various rotational speeds of the AMDs 102and locating a maximum efficiency point. In some embodiments, thecontroller 104 may operate at a high efficiency without direct powermeasurement such as, for example, by use of other parameters that varywith power or efficiency, monitoring rotational speed of the AMDs 102,etc. In some embodiments, the controller 104 is configured to maintain aminimum rotational speed for the AMDs 102 regardless of the efficiencyto ensure adequate cooling of the electronic system 100.

The selectable profiles may include a low acoustic noise profile.Several aspects were discussed above that may reduce acoustic noiseproduced by AMDs 102. The low acoustic noise profile may incorporate oneor more of the aforementioned aspects to reduce acoustic noise. The lowacoustic noise profile may also cause the controller 104 to operate theAMDs 102 at a rotational speed that will provide adequate cooling of theelectronic system 100. The temperature measured by the temperaturesensor 108 may be allowed to approach a maximum allowable temperaturefor the electronic system 100 under the low acoustic noise profile. Oneor more particular rotational speeds (or ranges of rotational speeds) ofthe AMDs 102 may be prohibited to the controller 104 under the lowacoustic noise profile. For example, certain frequencies may excite aresonance in the electronic system 100 and generate noticeable audiblenoise. By prohibiting the controller 104 from operating the AMDs 102 atthose frequencies, audible noise may be reduced.

The selectable profiles may include a maximum cooling profile. When themaximum cooling profile is selected, the controller 104 operates allAMDs 102 at their maximum rotational speed regardless of efficiency,noise, temperature, etc.

The selectable profiles may include a maximum AMD life profile.Typically, lower rotational speeds and lower ambient temperatures arebetter for extending the life of an air moving device than hightemperatures and/or high operating speeds. Operating the AMDs 102 atlower rotational speeds, however, may increase the ambient temperaturein the electronic system 100. Accordingly, under the maximum AMD lifeprofile, the controller 104 is configured to monitor the rotationalspeed of the AMDs 102 and the ambient temperature in the electronicsystem 100 to estimate the remaining life of the AMDs 102 (in the mannerdiscussed above). The controller 104 may also be configured to adjustthe rotational speed of the AMDs 102 to optimize the estimated remaininglife of the AMDs 102. The remaining life may also be estimated usinglook-up tables stored in the memory 106. In some embodiments, thecontroller 104 is configured to maintain a minimum rotational speed forthe AMDs 102 regardless of the affect on estimated remaining life toensure adequate cooling of the electronic system 100.

In any of the examples disclosed herein, the electronic system may beany electronic system that includes one or more air moving devices.Furthermore, the electronic system may be included as part of anotherelectronic system or systems (e.g., a host system). The electronicsystem may also control one or more air moving devices in such a hostsystem. For example, the electronic system may be a power supplyincluding one or more air moving devices controlled by a controller inthe power supply according to one or more aspects of this disclosure.Alternatively, or additionally, the power supply may be included as partof another system (e.g., a computer or other system to which the powersupply is supplying power). The power supply may additionally, oralternatively, control one or more air moving device in, for example,the computer hosting the power supply according to one or more aspect ofthis disclosure.

The controllers disclosed herein may be any suitable controller forcontrolling operation of an air moving device according to the variousaspects disclosed herein. The controller may be, for example, a digitalcontroller. The controller may be, for example a microprocessor, a DSP,etc. The controller may be a discrete component or may include more thanone discrete components operatively coupled together to function as acontroller disclosed herein. Further, the controller may include analogcomponents and/or digital components. In embodiments that includememory, the controller may include the memory or the memory may beseparate from the controller.

Although the aspects and embodiments disclosed herein are described withrespect to air moving devices, it should be understood that air movingdevices are generally electric motors with fan blades attached thereto.Various aspects of this disclosure may, accordingly, be applied to anyrotating mechanical device including, for example, electric motors.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. A method of controlling an air moving device inan electronic system, the air moving device including an electric motor,the air moving device operable to accelerate between rotational speedsat a maximum angular acceleration, the method comprising: whenincreasing the rotational speed of the air moving device including theelectric motor from a first rotational speed to a second rotationalspeed, limiting an angular acceleration of the air moving device to afirst acceleration limit less than the maximum angular acceleration; andwhen decreasing the rotational speed of the air moving device includingthe electric motor, limiting the angular acceleration of the air movingdevice to a second acceleration limit having an absolute value less thanthe maximum acceleration, wherein the first acceleration limit and theabsolute value of the second acceleration limit are different.
 2. Themethod of claim 1 further comprising, when changing the air movingdevice from a third rotational speed to a fourth rotational speed,limiting the angular acceleration of the air moving device to a thirdacceleration limit having an absolute value less than the maximumangular acceleration.
 3. The method of claim 2 wherein the firstacceleration limit and the third acceleration limit are not equal. 4.The method of claim 2 wherein the second rotational speed is greaterthan the first rotational speed and the third rotational speed isgreater than the fourth rotational speed.
 5. The method of claim 4wherein the third acceleration limit is greater than the firstacceleration limit.
 6. The method of claim 2 wherein the secondrotational speed is greater than the first rotational speed, the thirdrotational speed is equal to or greater than the second rotationalspeed, and the fourth rotational speed is greater than the thirdrotational speed.
 7. The method of claim 6 wherein the thirdacceleration limit is greater than the first acceleration limit.
 8. Amethod of controlling an air moving device in an electronic system, theair moving device including an electric motor, the air moving deviceoperable to accelerate between rotational speeds at a maximum angularacceleration, the method comprising: selectively controlling an angularacceleration of the air moving device including the electric motor whenchanging a rotational speed of the air moving device; limiting theangular acceleration of the air moving device to a first accelerationlimit less than the maximum angular acceleration when increasing therotational speed of the air moving device; and limiting the angularacceleration of the air moving device to a second acceleration limithaving an absolute value less than the maximum angular acceleration whendecreasing the rotational speed of the air moving device, wherein thefirst acceleration limit and the absolute value of the secondacceleration limit are different.
 9. The method of claim wherein anabsolute value of the second acceleration limit is greater than anabsolute value of the first acceleration limit.
 10. The method of claim8 wherein selectively controlling the angular acceleration of the airmoving device includes limiting the angular acceleration to a thirdacceleration limit when increasing the rotational speed of the airmoving device within a first range of rotational speeds and limiting theangular acceleration to a fourth acceleration limit when increasing therotational speed of the air moving device within a second range ofrotational speeds.
 11. The method of claim 10 wherein a lowestrotational speed within the second range of rotational speeds is greaterthan or equal to a highest rotational speed within the first range ofrotational speeds, and wherein the fourth acceleration limit is greaterthan the third acceleration limit.
 12. The method of claim 11 whereinthe fourth acceleration limit is approximately equal to the maximumangular acceleration.
 13. An electronic system comprising: an air movingdevice selectively operable to rotate at a plurality of speeds inresponse to a control signal, the air moving device having a maximumangular acceleration; and a controller communicatively coupled to theair moving device, the controller configured to generate the controlsignal and to selectively control an angular acceleration of the airmoving device through the control signal when changing a rotationalspeed of the air moving device, and to limit the angular acceleration ofthe air moving device to a first acceleration limit less than themaximum angular acceleration when increasing the rotational speed of theair moving device and limit the angular acceleration to a secondacceleration limit having an absolute value less than the maximumangular acceleration when decreasing the rotational speed of the airmoving device, wherein the first acceleration limit and the absolutevalue of the second acceleration limit are different.
 14. The electronicsystem of claim 13 wherein an absolute value of the first accelerationlimit is smaller than an absolute value of the second accelerationlimit.
 15. The electronic system of claim 13 wherein the controller isconfigured to limit the angular acceleration to a third accelerationlimit when increasing the rotational speed of the air moving devicewithin a first range of rotational speeds and limiting the angularacceleration to a fourth acceleration limit when increasing therotational speed of the air moving device within a second range ofrotational speeds.
 16. The electronic system of claim 15 wherein alowest rotational speed within the second range of rotational speeds isgreater than or equal to a highest rotational speed within the firstrange of rotational speeds, and wherein the fourth acceleration limit isgreater than the third acceleration limit.
 17. The electronic system ofclaim 13 wherein the controller is configured to increase the angularacceleration of the air moving device while increasing the rotationalspeed of the air moving device.
 18. The electronic system of claim 13further comprising a memory device, the memory device storing programcode having instruction executable by the controller to generate thecontrol signal and to selectively control the angular acceleration ofthe air moving device through the control signal when changing therotational speed of the air moving device.